Professor Sebastian Wieczorek
Biography
Sebastian M. Wieczorek received his MSc degree in Theoretical Physics from Adam Mickiewicz University in Poznan, Poland, in 1998, and his PhD degree in Mathematical Physics from the Vrije Universiteit Amsterdam, The Netherlands, in 2002. Following his PhD, he worked as a Researcher at Sandia National Laboratories in Albuquerque, New Mexico, USA, for the Department of Energy and the Lockheed Martin Corporation. He was then appointed Lecturer in Mathematics at the University of Exeter, UK, in June 2006, promoted to Senior Lecturer in May 2010, and to Associate Professor in February 2014. In August 2014, Sebastian took the position of Professor (Chair) of Applied Mathematics and Head of Applied Mathematics at University College Cork.
Research Interests
Professor Sebastian Wieczorek specialises in Applied Nonlinear Dynamics and Bifurcation Theory or, in other words, in the mathematical theory of instability. He develops mathematical concepts and techniques for physical problems including:
 Nonlinear dynamics of semiconductor laser systems.
 Tipping Points (Critical Transitions) in the climate and ecosystems.
 Instabilities in the brain (e.g. seizure dynamics).
 Stability of healthcare systems.
 Nonlinear dynamics of evolutionary games.
Google Scholar profile of Prof. Sebastian Wieczorek: https://scholar.google.co.uk/citations?user=oklPBYAAAAJ
Research Examples
Stability diagram of coupled semiconductor lasers
Coupled semiconductor lasers are used in modern applications ranging from communication schemes to random number generation, and medicine. As the coupling between lasers increases (going from bottom to top) their behaviour changes from regular (yellowred) to chaotic or unpredictable (shades of grey). Complexity of
such transitions is aesthetically pleasing but mathematically challenging.
ShearInduced Bifurcations and Chaos in Models of Three Coupled Lasers: SIAM Journal on Applied Dynamical Systems
Rateinduced tipping points
Rateinduced tipping points describe the failure of a physical system to adapt to changing external conditions. When external conditions vary in time, the position of the
stable equilibrium "a" changes, and the system tries to track the moving equilibrium. However, if external conditions vary too fast, systems will fail to track the moving equilibrium and may suddenly go to another (undesired) state. Mathematically, these are nonautonomous instabilities that cannot, in general, be captured by the traditional stability theory. Thus, they require an alternative approach. The example illustrates the compostbomb instability: a sudden and unexpected release of soil carbon C from peatlands into the atmosphere above some critical rate of warming. This instability involves a nonobvious threshold: (blue curve) a canard trajectory through a folded saddle singularity "F".
Shearinduced chaos in perturbed lasers.
Lasers are light amplifiers that consist of an optical resonator filled with an active medium. Parameter alpha, also known as the linewidth enhancement factor, arises from the dependence of the laser resonant frequency on the number of excited electrons, N, in the active medium. Mathematically, alpha quantifies the amount of shear in the laser phase space or amplitudedependent frequency. (Right panel) Nonzero shear about the lasing solution (red limit cycle) gives rise to stretchandfold action. This is similar to the action of a horseshoe map a hallmark of deterministic chaos.
SPIE Newsroom article
DSWeb Magazine article
Short CV
From  To  Details 

20140701  2017  Honorary Professor at University of Exeter, UK 
20140701  2017  Head of Department of Applied Mathematics at University College Cork, Ireland 
20140701  Professor (Chair) of Applied Mathematics at University College Cork, Ireland  
20140201  Associate Professor of Applied Mathematics at University of Exeter, UK  
20100501  Senior Lecturer in Mathematics at University of Exeter, UK  
20060601  2017  Lecturer in Mathematics at University of Exeter, UK 
20021101  20060701  Postdoc at Sandia National Laboratories, Albuquerque, NM, USA with Prof. Weng W. Chow 
20020423  Ph.D. degree (cum laude) in Mathematical Physics Vrije Universiteit Amsterdam (VU), The Netherlands Thesis supervisor: Prof. Dr Daan Lenstra Thesis cosupervisor: Prof. Dr Bernd Krauskopf Thesis: "The dynamical complexity of optically injected semiconductor lasers" Physics Reports, 416, 12, (2005) 1128 

19980708  M.Sc. degree (UAM medal) in Theoretical Physics Adam Mickiewicz University (UAM) in Poznan, Poland Supervisor: Prof. Dr. Ryszard Parzynski Thesis: "Interference stabilization of Rydberg atoms enhanced by multiple Vtype resonances" Physical Review A, 58, 4, (1998) 30513057 
Publications
Book Chapters of Sebastian Wieczorek:
1. S. Wieczorek,
"Global Bfurcation Analysis in Laser Systems" +
in Numerical Continuation Methods for Dynamical Systems: Path following and boundary value problems,
B. Krauskopf, H.M. Osinga and J. GalanVioque (Eds.),
SpringerVerlag (2007), 177220.
2. S. Wieczorek,
"Noise synchronisation and stochastic bifurcations in lasers" +
in Nonlinear Laser Dynamics  From Quantum Dots to Cryptography
Kathy Ludge (Ed. ),
WileyVCH Verlag (2012), 271290. http://arxiv.org/abs/1104.4052
Papers of Sebastian Wieczorek in Journals:
1. R. Parzynski and S. Wieczorek,
"Interference stabilization of Rydberg atoms enhanced by multiple Vtype resonances",
Physical Review A 58 4 (1998) 30513057 +
2. S. Wieczorek, B. Krauskopf, and D. Lenstra,
"A unifying view of bifurcations in a semiconductor laser subject to optical injection",
Optics Communications 172 (1999) 279295 +
3. S. Wieczorek, B. Krauskopf, and D. Lenstra,
"Mechanisms for multistability in a semiconductor laser with optical injection",
Optics Communications 183 (2000) 215226 +
4. B. Krauskopf, S. Wieczorek, and D. Lenstra,
"Different types of chaos in an optically injected semiconductor laser",
Applied Physics Letters 77 (11) (2000) 16111613 +
5. S. Wieczorek, B. Krauskopf, and D. Lenstra,
"Sudden chaotic transitions in an optically injected semiconductor laser",
Optics Letters 26 (11) (2001) 816818 +
6. S. Wieczorek, .B. Krauskopf, and D. Lenstra,
"Unnested islands of perioddoublings in an injected semiconductor laser",
Physical Review E 64 056204 (2001) 18 +
7. S. Wieczorek, B. Krauskopf, and D. Lenstra,
``Multipulse excitability in a semiconductor laser with optical injection''
Physical Review Letters 88 063901 (2002) 14 +
8. S. Wieczorek, T.B. Simpson, B. Krauskopf, and D. Lenstra,
"Global quantitative predictions of complex laser dynamics''
Physical Review E 66 045207 (Rapid Communications) (2002) +
9. B. Krauskopf and S. Wieczorek,
"Accumulating regions of winding periodic orbits in optically driven lasers''
Physica D 173 (12) (2002) 97113 +
10. B. Krauskopf, K. Schneider, J. Sieber, S. Wieczorek, and M. Wolfrum,
"Excitability and selfpulsations near homoclinic bifurcations in semiconductor laser systems''
Optics Communications 215 (46) (2003) 367379 +
11. S. Wieczorek, T. B. Simpson, B. Krauskopf, and D. Lenstra,
"Bifurcation transitions in an optically injected diode laser: theory and experiment''
Optics Communications 215 (2003) 125134 +
(see the experimental companion paper by T.B. Simpson) +
12. S. Wieczorek and D. Lenstra,
"Spontaneously excited pulses in an optically driven semiconductor laser''
Physical Review E 69 016218 (2004) 15 +
13. S. Wieczorek and W.W. Chow,
"Bifurcations and interacting modes in coupled lasers: A strong coupling theory''
Physical Review A 69 033811 (2004) 117 +
14. S. Wieczorek and W.W. Chow,
"Chaos in practicallyisolated lasers''
Physical Review Letters 92 213901 (2004) 14 +
15. S. Wieczorek, W. W.Chow, S.R. Lee, A.J. Fisher, A. Allerman, and M.H. Crawford,
"Analysis of optical emission from highaluminium AlGaN quantumwell structures''
Applied Physics Letters 84 (24) (2004) 48994901 +
16. S. Wieczorek and B. Krauskopf,
"Bifurcations of nhomoclinic orbits in optically injected lasers''
Nonlinearity 18 (2005) 10951120 +
17. S. Wieczorek and W.W. Chow,
"Global view of nonlinear dynamics in coupledcavity lasersa bifurcation study"
Optics Communications 246 (46) (2005) 471493 +
18. S. Wieczorek, B. Krauskopf, T.B. Simpson, and D. Lenstra,
"The dynamical complexity of optically injected semiconductor lasers"
Physics Reports 416 (12) (2005) 1128 +
19. S. Wieczorek, W.W. Chow, L. Chrostowski, and C. J. ChangHasnain
"Improved semiconductorlaser dynamics from induced population pulsation"
IEEE Journal of Quantum Electronics 42 (6) (2006) 552562 +
20. S. Wieczorek and W. W. Chow,
"Selfinduced chaos in a singlemode inversionless laser"
Physical Review Letters 97 113903 (2006) 14 +
21. L. Chrostowski, B. Faraji, W. Hoffmann, M.C. Amann, S. Wieczorek and W. W. Chow,
"40 GHz bandwidth and 64 GHz resonance frequency in injectionlocked 1.55 microm VCSELs"
IEEE Journal of Selected Topics in Quantum Electronics 13 (5) (2007) 12001208
22. H. Erzgraber, S. Wieczorek, and B. Krauskopf,
"Dynamics of two laterally coupled semiconductor lasers: strong and weakcoupling theory"
Physical Review E 78 066201 (2008) 119 +
23. S. Wieczorek and W. W. Chow,
"Bifurcations and chaos in a semiconductor with coherent or noisy optical injection"
Optics Communications 282 (12)(2009) 23672379 +
24. S. Wieczorek,
"Stochastic bifurcation in noisedriven lasers and Hopf oscillators"
Physical Review E 79 036209 (2009) 110 +
25. W.W. Chow and S. Wieczorek,
"Using chaos for remote sensing of laser radiation"
Optics Express 17 (9) (2009) 74917504 +
26. H. Erzgraber, S. Wieczorek, and B. Krauskopf,
"Locking of three coupled laser oscillators"
Physical Review E 80 026212 (2009) 16 +
27. H. Erzgraber, S. Wieczorek, and B. Krauskopf,
"Dynamics of two semiconductor lasers coupled by a passive resonator"
Physical Review E 81 056201 (2010) 113 +
28. L. Olejniczak, K. Panajotov, S. Wieczorek, H. Thienpont, M. Sciamanna,
"Intrinsic gain switching in optically injected quantum dot laser lasing simultaneously from the ground and excited state"
Journal of Optical Society of America B 27 (11) (2010) 24162423 +
29. S. Wieczorek, P. Ashwin, C.M. Luke, and P. Cox,
"Excitability in ramped systems: the compostbomb instability"
Proceedings of The Royal Society A 467 (May 8 2011) 12431269 +
CBS NEWS article
ScienceDaily article
Exeter University Press Release
30. N. Blackbeard, H. Erzgraber, and S. Wieczorek,
"Shearinduced bifurcations and chaos in coupledlaser models"
SIAM Journal on Applied Dynamical Systems 10 (2) (2011) 469509 +
DSWeb magazine article (multimedia)
31. P. Ashwin, S. Wieczorek, R. Vitolo, and P. Cox
"Tipping points in open systems: bifurcation, noiseinduced and ratedependent examples in the climate system"
Philosophical Transaction of The Royal Society A 370 (2012) 11661184+
32. B. de Saedeleer, M. Crucifix and S. Wieczorek
"Is the astronomical forcing a reliable and unique pacemaker for Climate? Aconceptual model study."
Climate Dynamics 40 (12) (2013) 273294 +
33. N. Blackbeard, S. Wieczorek, H. Erzgraber, P.S. Dutta
"From synchronisation to optical turbulence in laser arrays"
Physica D 286287 (2014) 4358 +
34. C. Perryman and S. Wieczorek,
Adapting to a Changing Environment: Nonobvious Thresholds in Multiscale Systems"
Proceedings of the Royal Society A 470 20140226 (8 Oct 2014) 116 + +
35. P. Slowinnski, B. Krauskopf and S. Wieczorek,
"Mode structure of a semiconductor laser with feedback from two external filters"
Discrete and Continuous Dynamical Systems B 20(2) (March 2015) 519586 + ++
36. S. Wieczorek, K. Synnott and W.W. Chow,
(Invitetd paper) "Stability of newgeneration semiconductor lasers
SPIE Newsroom (2016)
37. P. Ashwin, C. Perryman and S. Wieczorek
"Parameter shifts for nonautonomous systems in low dimension: Bifurcation and Rateinduced tipping"
Nonlinearity 20 (April 2017) 21852210 + ++
Selected for 2017 Nonlinearity Highlights Collection
38. A. Marchionne, P. Ditlevsen and S. Wieczorek
"Synchronisation vs. Resonance: Isolated Resonances in Damped Nonlinear Oscillators"
Physica D, 380381 (2018) 816 +
39. A. Vanselow, S. Wieczorek and U. Feudel
"When very slow is too fast  collapse of a predatorprey system"
Journal of Theoretical Biology, 479 (2019) 6472 + ++
Preprints of Sebastian Wieczorek:
40. P.E. O'Keeffe and S. Wieczorek
"Tipping Phenopmena and Points of No Return in Ecosystems: Beyond Classical Bifurcations"
arXiv preprint (2019) 144. +
41. S. Wieczorek, Ch. Xie and C.K.R.T. Jones
"Compactification for Asymptotically Autonomous Dynamical Systems: Theory, Applications and Invariant Manifolds"
arXiv preprint (2020) 131.
42. S. Wieczorek and W. W. Chow,
"Stabilising and destabilising effects of polarisation dynamics in class C lasers with optical external injection or timedelayed feedback" (preprint)
Papers of Sebastian Wieczorek in Proceedings:
1. Bernd Krauskopf, Sebastian Wieczorek, and Daan Lenstra,
"Routes to chaos in an optically injected semiconductor laser",
Proceedings of SPIE 3944 (2000) 612619
2. Sebastian Wieczorek, Bernd Krauskopf, and Daan Lenstra,
"Global view of complicated dynamics in optically injected semiconductor laser",
Proceedings of SPIE 3944 (2000) 602611
3. Sebastian Wieczorek, Bernd Krauskopf, and Daan Lenstra,
"Multistability in optically injected semiconductor laser",
Proceedings of CLEO/Europe 2000
4. Sebastian Wieczorek, Bernd Krauskopf, and Daan Lenstra,
"Bifurcations of chaotic attractors in a semiconductor laser subject to optical injection",
Proceedings of LEOS (2000) 6465
5. Sebastian Wieczorek, Thomas B. Simpson, Bernd Krauskopf, and Daan Lenstra,
"Complex dynamics of an optically injected semiconductor laser: bifurcation theory and experiment",
Proceedings of SPIE 4646 (2002) 471478
6. Bernd Krauskopf, Sebastian Wieczorek, and Daan Lenstra,
"Multipulse excitability in injected lasers",
Proceedings of SPIE 4986 (2003) 432439
7. T.B. Simpson, S. Wieczorek, B. Krauskopf, and Daan Lenstra,
"Mapping the complex dynamics of a semiconductor laser subject to optical injection"
AIP Conference Proceedings 676 (2003) 375
8. D. Lenstra, B. Krauskopf, G. Vemuri, S. Wieczorek, and M. Yousefi,
"The influence of noise on the dynamics of semiconductor lasers",
Proceedings of SPIE 5468 (2004) 165.
9. S. Wieczorek, and W. W. Chow,
"Dynamics of multimode coupled lasers"
Proceedings of SPIE 5452 (2004) 7181.
10. P. Slowinski, B. Krauskopf and S.M. Wieczorek,
"Mode structure of a semiconductor laser with feedback from two external filters"
Proceedings of SPIE 6997 (2008)
11. H. Erzgraber, S.M. Wieczorek and B. Krauskopf,
"Bifurcations of compositecavity modes in multistripe laser arrays
Proceedings of SPIE 6997 (2008)
12. S. Wieczorek,
(Invitetd paper) "Sensitivity of semiconductor lasers to coherent and noisy optical injection: Towards instabilitybased sensors".
Proceedings of SPIE 721105 (2009)
13. S. Wieczorek, K. Synnott and W.W. Chow,
(Invitetd paper) "Stability of newgeneration semiconductor lasers
SPIE Newsroom (2016)